This is an example of the glitch. As you can see, two engines are working fine, the other two are pulsating white boxes. This happens on the Hareeb cruiser as well. It kind of ruins the aesthetic of the Nomads for me, which is … really what I like about them.
A simple forum search with terms “nomad engine problem” would have eventually led you to this older Support thread. Read with care. Let us know if this solves the flaw for you.
I wonder if, like the poor soul who first found this problem, you also purchased GSB through Impulse? And which version number of the game are you running? That # appears in the top-right corner of the startup screen - v1.55 is the latest.
BTW you somehow rediscovered a very unccommon problem; I’m glad that I recalled it when i saw your request for help.